It's the virtual 8086 mode that virtualizes multiple DOS instances. Windows 3.x gets very intimate with DOS to implement this feature (maintaining multiple pa

It's the virtual 8086 mode that virtualizes multiple DOS instances. Windows 3.x gets very intimate with DOS to implement this feature (maintaining multiple parallel DOS states) and FreeDOS doesn't mirror DOS precisely enough for this to work. But a clever hacker just just patched it a few months ago. So now it works, kinda: https://sourceforge.net/p/freedos/mailman/message/37326256/ https://sourceforge.net/p/freedos/mailman/message/37326256/